tweeting a favorite picture of bill clinton wrote, i'll never forget my friend. using the affectionate name by which he was known to his followers. prince william and his wife, duchess of cambridge, were at the film, "long walk to freedom." >> tragic news. we're reminded of what an extraordinary and inspiring man nelson mandela was and my thoughts and prayers are with him and his family right now. >> reporter: tonight britain's prime minister david cameron. >> tonight one of the brightest lights of our world has gone out. nelson mandela was not just a hero of our time, but a hero of all-time. >> reporter: president bush 41 wrote as president i watched in wonder as nelson mandela had the remarkable capacity to forgive his jailers. setting a powerful example of redemption and grace for us all. president george w. bush wrote president mandela was one of the great forces for freedom and equality of our time. mandela set an example by visiting new zealand, forgiving the country that sent its rugby team to play south africa during the apartheid years. tonight the prime